Enhanced Li storage of pure crystalline-C_(60) and TiNb_(2)O_(7)-nanostructure composite for Li-ion battery anodes

We propose a method for producing composite materials(hTNO@C_(60))comprising crystalline C_(60)particles and hollow-structu red TiNb_(2)O_(7)(hTNO)nanofibers via facile liquid-liquid interface precipitation followed by low-temperature annealing.This allows the systematic design of crystalline C_(60)as an active material for Li-ion battery anodes.The hTNO@C_(60)composite demonstrates outstanding cyclic stability,retaining a capacity of 465 mA h g^(-1)after 1,000 cycles at 1 A g^(-1)It maintains a capacity of 98 mA h g^(-1)even after16,000 ultralong cycles at 8 A g^(-1)The enhancement in electrochemical properties is attributed to the successful growth and uniform doping of crystalline C_(60),resulting in improved electrical conductivity.The excellent electrochemical stability and properties of these composites make them promising anode materials.

Electrodeposition and characterization of nanocrystalline Fe-Ni-Cr alloy coatings synthesized via pulse current method

The nanocrystalline Fe-Ni-Cr coatings were electrodeposited by using the pulse current technique.The SEM results showed that the coatings had a mixed morphology of small nodules and fine cauliflower structures at low current densities.Also,the Cr content was increased at expense of Fe and Ni contents at high current densities.XRD patterns confirmed that the pulse current density had a positive effect on the grain refinement.The results of vibrating sample magnetometer(VSM)measurements demonstrated that by increasing the current density,the saturation magnetization was decreased and the coercivity was increased due to the enhancement of Cr content and the reduction of the grain size.The friction coefficient and wear rate values were decreased by increasing the pulse current density.Also,both the adhesive and abrasive wear mechanisms were observed on the worn surfaces.The abrasive grooves and the amount of wear debris were decreased by increasing the pulse current density.

Interfacial engineering through lead binding using crown ethers in perovskite solar cells

In the domain of perovskite solar cells(PSCs),the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative solutions.This study pioneers an approach that not only rectifies lead leakage but also places paramount importance on the attainment of rigorous interfacial passivation.Crown ethers,notably benzo-18-crown-6-ether(B18C6),were strategically integrated at the perovskite-hole transport material interface.Crown ethers exhibit a dual role:efficiently sequestering and immobilizing Pb^(2+)ions through host-guest complexation and simultaneously establishing a robust interfacial passivation layer.Selected crown ether candidates,guided by density functional theory(DFT)calculations,demonstrated proficiency in binding Pb2+ions and optimizing interfacial energetics.Photovoltaic devices incorporating these materials achieved exceptional power conversion efficiency(PCE),notably 21.7%for B18C6,underscoring their efficacy in lead binding and interfacial passivation.Analytical techniques,including time-of-flight secondary ion mass spectrometry(ToF-SIMS),ultraviolet photoelectron spectroscopy(UPS),time-resolved photoluminescence(TRPL),and transient absorption spectroscopy(TAS),unequivocally affirmed Pb^(2+)ion capture and suppression of non-radiative recombination.Notably,these PSCs maintained efficiency even after enduring 300 h of exposure to 85%relative humidity.This research underscores the transformative potential of crown ethers,simultaneously addressing lead binding and stringent interfacial passivation for sustainable PSCs poised to commercialize and advance renewable energy applications.

Microstructure of fast tool servo machining on copper alloy

The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the FTS.The excessive driving frequency increases the formation of burrs.The effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.

Portable nano probe for micro/nano mechanical scratching and measuring

A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine measuring applications and one kind of contact type measuring probes was designed for miniaturized or microfactory system. It ideally should be of small size and able to measure surface topography in nanometer scale. A commercial capacitive displacement sensor was proposed. It was a new concept in nano probe systems which can measure the displacement of shaft driven by the variation of surface topography. The nano probe mainly consisted of three parts： a capacitive displacement sensor, a porous type air slide and a contact probe part with various tip radiuses. The porous type air slide assured the shaft slided smoothly with controllable normal force in mN scale and had high positioning accuracy. The probe part which was directly in contact with target surface, can be applied to micro/nanoscale scratching as well as the measurement of sample topography by a simple tip change.

Diamond machining of sinusoidal grid surface using fast tool servo system for fabrication of hydrophobic surface

Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.

Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

摩擦搅拌焊参数对超细晶Al-0.2 wt%Sc合金薄板微观组织和热力学性能的影响

为了研究摩擦搅拌焊参数对超细晶粒Al-Sc合金薄板微观组织、热力学性能的影响,采用累积滚焊法(ARB)制备的超细晶粒Al-Sc合金薄板进行了摩擦搅拌焊数值模拟。此外,研究了刀具转速、焊接速度和刀具倾斜角等摩擦搅拌焊参数的最优条件。在SYSWELD和Visual-Environment软件中实现了数值模拟,并通过实验结果进行了验证。结果表明,摩擦搅拌焊是一种有利于保持超细晶(UFG)组织的技术,并在累积滚焊材料中具有较好的力学性能。刀具转速对热性能和力学性能的影响最大。在刀具转速为700 r/min、焊接速度为80 mm/min、刀具倾斜角度为3°时,Al-Sc合金的硬度和抗屈强度均达到最高。

Superior electrocatalytic negative electrode with tailored nitrogen functional group for vanadium redox flow battery

Development of electrodes with high electrocatalytic activity and stability is essential for solving problems that still restrict the extensive application of vanadium redox flow batteries(VRFBs).Here,we designed a novel negative electrode with superior electrocatalytic activity by tailoring nitrogen functional groups,such as newly formed nitro and pyridinic-N transformed to pyridonic-N,from the prenitrogen-doped electrode.It was experimentally confirmed that an electrode with pyridonic-N and nitro fuctional groups(tailored nitrogen-doped graphite felt,TNGF) has superior electrocatalytic acivity with enhanced electron and mass transfer.Density functional theory calulations demonstrated the pyridonic-N and nitro functional groups promoted the adsorption,charge transfer,and bond formation with the vanadium species,which is consistent with expermental results.In addition,the V2+/V3+redox reaction mechanism on pyridonic-N and nitro functional groups was estabilised based on density functional theory(DFT) results.When TNGF was applied to a VRFB,it enabled enhanced-electrolyte utilization and energy efficiencies(EE) of 57.9% and 64.6%,respectively,at a current density of 250 mA cm^(-2).These results are 18.6% and 8.9% higher than those of VRFB with electrode containing graphitic-N and pyridinicN groups.Interestingly,TNGF-based VRFB still operated with an EE of 59% at a high current density of300 mA cm^(-2).The TNGF-based VRFB exhibited stable cycling performance without noticeable decay of EE over 450 charge-discharge cycles at a current density of 250 mA cm^(-2).The results of this study suggest that introducing pyridonic-N and nitro groups on the electrode is effective for improving the electrochemical performance of VRFBs.

Developing a two-decadal time-record of rice field maps using Landsat-derived multi-index image collections with a random forest classifier:A Google Earth Engine based approach

Historic maps showing the temporal distribution of rice fields are important for precision agriculture,irrigation optimisation,forecasting crop yields,land use management and formulating policies.However,mapping rice felds using traditional ground surveys is impractical when high cost,time and labour requirements are considered,and the availability of such detailed records is limited.Although satellite remote sensing appears to be a viable solution,conventional segmentation and classification methods with spectral bands are often unable to contrast the distinct characteristics between rice fields and other vegetation classes.To this end,we explored a novel,Google Earth Engine(GEE)based multiindex random forest(RF)classification approach to map rice fields over two decades.Landsat images from 2000 to 2020 of two Sri Lankan rice cultivation districts were extracted from GEE and a multi-index RF classification algorithm was applied to distinguish the rice fields.The results showed above 80%accuracy for both training and validation,when compared against high spatial resolution Google Earth imagery.In essence,multi-index sampling and RF together synergised the compelling classifcation accuracy by effectively capturing vegetation,water(ponding)and soil characteristics unique to the rice felds using a single-click approach.The maps developed in this study were further compared against the MODIS land cover type product(MCD12Q1)and the corresponding superior statistics on rice fields demonstrated the robustness of the proposed approach.Future work seeking effective index combinations is recommended,and this approach can potentially be extended to other crop analyses elsewhere.

Nacro_2 Electrode for Rechargeable Sodium Ion Batteries

Layered lithium intercalation compounds LiMeO_2(Me:transition element)materials have been widely studied and applied as cathode materials for practical lithium ion batteries.Cost of lithium resource,however,has doubled since commercialization in 1991,and tight supply is expected due to the ever increasing demands of elec-

Macroscopic Ag nanostructure array patterns with high-density hotspots for reliable and ultra-sensitive SERS substrates

Syn thesis of metal nano structures arrays with large amounts of small nano-gaps on a homoge nous macroscale is of significant in terest and importa nee in chemistry,biotech no logy,physics,and nan otech no logy because of their enhan ced properties.However,the fabricatio n of uncovered nano-gaps with high-density and uniformity is rather difficult due to the complex and multiple synthetic steps.In this research,a facile and low-cost approach is demonstraind for the synthesis of high-density small nano-gaps(about 3.4 nm)between silver nanostructure array patter ns(SNAPs)over a large area.Uniform nan o?hole patter ns were periodically gen erated over an entire substrate using nano-impri nt lithography.Electrochemical reacti on at the high over-potential produced multiple silver nano crystals inside the nano-hole patter ns,gen erati ng a high-de nsity of small and un covered nano-gaps.Finally,we fully dem on strate their applicati on in the rapid detectio n of rhodamine 6G(R6G)molecules by surface-enhaneed Raman scattering(SERS)spectroscopy with a very low detection limit(1 fM)as well as excellent signal uniformity(RSD<8.0%±2.5%),i ndicati ng an extra ordinary capability for single-molecule detecti on.

Enhancement of magnetic properties of hot pressed/die-upset Dy-free Nd-Fe-B magnets with Cu/Nd coating by wet process

A grain boundary diffusion process(GBDP)was adopted to improve magnetic properties of Dy-free highly coercive Nd-Fe-B permanent magnet by coating thin layers of Nd and Cu in grain boundaries.For GBDP of Nd and Cu,Nd and Cu were coated by wet process,e.g.,electrochemical and electroless on Nd-Fe-B magnets,which was fabricated by hot-deformed/die-upset with meltspun specimen.Heat treatment was performed for 20 min at 600℃followed by several different cooling conditions.The cooling conditions after heat treatment were varied to understand distribution and micros tructural effects of Nd and Cu species in grain boundaries.The coercivity increased from 1.565 to 1.637 T in oil cooling rate but remanence decreased,while remanence jumped with little decrease in coercivity in furnace cooling.Micros tructure analyses suggested that the coercivity was closely related to the cooling rate as well as distribution of Nd.The mechanism of coercivity enhancement due to the cooling rate was discussed based on the results presented here and those in the literature.

Recent Advances in Electrode Materials with Anion Redox Chemistry for Sodium-Ion Batteries

The development of sodium-ion batteries(SIBs),which are promising alternatives to lithium-ion batteries(LIBs),offers new opportunities to address the depletion of Li and Co resources;however,their implementation is hindered by their relatively low capacities and moderate operation voltages and resulting low energy densities.To overcome these limitations,considerable attention has been focused on anionic redox reactions,which proceed at high voltages with extra capacity.This manuscript covers the origin and recent development of anionic redox electrode materials for SIBs,including state-of-the-art P2-and O3-type layered oxides.We sequentially analyze the anion activity–structure–performance relationship in electrode materials.Finally,we discuss remaining challenges and suggest new strategies for future research in anion-redox cathode materials for SIBs.